Tectono-stratigraphic terranes and the metamorphic history of the northeastern part of the crystalline core of the North Cascades: evidence from the Twisp Valley Schist

1993 ◽  
Vol 30 (7) ◽  
pp. 1306-1323 ◽  
Author(s):  
Robert B. Miller ◽  
Donna L. Whitney ◽  
Edward E. Geary
Keyword(s):  
Time History ◽  
Eastern Coast ◽  
North Cascades ◽  
Northeastern Part ◽  
The Core ◽  
Metamorphic History ◽  
The North ◽  
Crystalline Core ◽  
History Of ◽  
Geochemical Analyses

The Twisp Valley Schist (TVS) is important for both the correlation of terranes in the Cascades crystalline core and for the determination of the metamorphic pressure–temperature–time history of the northeastern part of the core. The TVS is a chaotically mixed unit of mainly siliceous schist (metachert) with significant amounts of metabasite, calc-silicate rock, and marble, and minor ultramafite and metapsammite. Geochemical analyses of metabasites indicate that the TVS contains both ocean-island basalts (OIB) and mid-ocean-ridge basalts (MORB). The TVS is lithologically similar to the Napeequa unit of the Chelan Mountains terrane in the Cascades core and is broadly correlative with units outside of the core, including the Mississippian–Jurassic Bridge River – Hozameen terrane of the eastern Coast belt, and coeval OIB-bearing terranes in the Northwest Cascades thrust system. Much of the northeastern Cascades core thus consists of oceanic rocks that probably originally lay between the Insular and the Intermontane superterranes, or were part of the latter superterrane.The TVS experienced polyphase deformation and greenschist to middle amphibolite facies metamorphism during the interval from 90 Ma (and possibly earlier) to ca. 50 Ma. Paleocene (ca. 65–58 Ma) dynamothermal metamorphism is the best documented event and in part resulted from forcible emplacement of plutons and from broadly distributed deformation in the Ross Lake fault zone. Major crustal loading of the TVS is inferred from the replacement of andalusite by kyanite, the presence of garnets that record an increase in pressure of 1.5–3.0 kbar (1 kbar = 100 MPa) from cores to rims, and the deeper emplacement levels of younger plutons. Loading may record thrusting in the northeastern core that is bracketed between 88 and 65 Ma and is younger than previously recognized, major contractional deformation in the North Cascades.

Tectonic implications of syn- and post-emplacement deformation of the Mount Stuart batholith for mid-Cretaceous orogenesis in the North Cascades

1992 ◽  
Vol 29 (3) ◽  
pp. 479-485 ◽  
Author(s):  
Robert B. Miller ◽  
Scott R. Paterson
Keyword(s):  
British Columbia ◽  
High Temperature ◽  
Main Part ◽  
North Cascades ◽  
Geochronological Data ◽  
The Core ◽  
The North ◽  
Crystalline Core ◽  
Thrust System ◽  
Unknown Period

The 93–96 Ma Mount Stuart batholith intruded across the boundary between the Northwest Cascades thrust system and the crystalline core of the North Cascades. Although previously considered posttectonic, the northeast margin of the Mount Stuart batholith and its wall rocks have been involved in syn- to post-emplacement, southwest-directed thrusting and folding, and west-northwest stretching. Contraction ended shortly after emplacement, as indicated by high-temperature recrystallization in thrust-related mylonites of the pluton and by geochronological data, whereas west-northwest stretching continued for an unknown period of time. This is the best documented mid-Cretaceous contractional belt in the main part of the crystalline core. The shortening direction and timing are identical to that of southwest-vergent thrusts in the offset continuation of the core in British Columbia. The contractional belt provides a link between thrusting in the Northwest Cascades thrust system and deformation in the crystalline core.

A Note on the Shipbuilding in Bengal in the Late Eighteenth Century

Itinerario ◽  
1995 ◽  
Vol 19 (3) ◽  
pp. 167-174 ◽  
Author(s):  
Bhaswati Bhattacharya
Keyword(s):  
Eighteenth Century ◽  
Early Modern ◽  
Direct Evidence ◽  
Early Modern Period ◽  
Eastern Coast ◽  
Shipbuilding Industry ◽  
The North ◽  
Indian Ocean Trade ◽  
History Of ◽  
The Indian Ocean

Both overseas trade and shipbuilding in India are of great antiquity. But even for the early modern period, maritime commerce is relatively better documented than the shipbuilding industry. When the Portuguese and later the North Europeans entered the intra-Asian trade, many of the ships they employed in order to supplement their shipping in Asia were obtained from the Indian dockyards. Detailed evidence with regard to shipbuilding, however, is very rare. It has been pointed out that the Portuguese in the sixteenth century were more particular than their North-European counter-parts in the following centuries in providing information on seafaring and shipbuilding. Shipbuilding on the west coast has been discussed more than that on the eastern coast of India, particularly the coast of Bengal. Though Bengal had a long tradition of shipbuilding, direct evidence of shipbuilding in the region is rare. Many changes were brought about in the history of India and the Indian Ocean trade of the eighteenth century, especially after the 1750s. When the English became the largest carriers of Bengal's trade with other parts of Asia, this had an impact on the shipbuilding in Bengal. It was in their interest that the British in Bengal had their ships built in that province.

Rb–Sr geochronology and metamorphic history of Proterozoic to early Archean rocks north of the Cape Smith Fold Belt, Quebec

1987 ◽  
Vol 24 (4) ◽  
pp. 813-825 ◽  
Author(s):  
Ronald Doig
Keyword(s):  
Volcanic Rocks ◽  
Granitic Rocks ◽  
Iron Formation ◽  
Fold Belt ◽  
Metasedimentary Rocks ◽  
Metamorphic History ◽  
The North ◽  
Basement Rocks ◽  
History Of ◽  
Wide Zone

The Churchill Province north of the Proterozoic Cape Smith volcanic fold belt of Quebec may be divided into two parts. The first is a broad antiform of migmatitic gneisses (Deception gneisses) extending north from the fold belt ~50 km to Sugluk Inlet. The second is a 20 km wide zone of high-grade metasedimentary rocks northwest of Sugluk Inlet. The Deception gneisses yield Rb–Sr isochron ages of 2600–2900 Ma and initial ratios of 0.701–0.703, showing that they are Archean basement to the Cape Smith Belt. The evidence that the basement rocks have been isoclinally refolded in the Proterozoic is clear at the contact with the fold belt. However, the gneisses also contain ubiquitous synclinal keels of metasiltstone with minor metapelite and marble that give isochron ages less than 2150 Ma. These ages, combined with low initial ratios of 0.7036, show that they are not part of the basement, as the average 87Sr/86Sr ratio for the basement rocks was about 0.718 at that time.The rocks west of Sugluk Inlet consist mainly of quartzo-feldspathic sediments, quartzites, para-amphibolites, marbles, and some pelite and iron formation. In contrast to the Proterozoic sediments in the Deception gneisses, these rocks yield dates of 3000–3200 Ma, with high initial ratios of 0.707–0.714. These initial ratios point to an age (or a provenance) much greater than that of the Archean Deception gneisses. The rocks of the Sugluk terrain are intruded by highly deformed sills of granitic rocks with ages of about 1830 Ma, demonstrating again the extent and severity of the Proterozoic overprint. The eastern margin of this possibly early Archean Sugluk block is a discontinuity in age, lithology, and geophysical character that could be a suture between two Archean cratons. It is not known if such a suturing event is of Archean age, or if it is related to the deformation of the Cape Smith Fold Belt.Models of evolution incorporating both the Cape Smith Belt and the Archean rocks to the north need to account for the internal structure of the fold belt, the continental affinity of many of the volcanic rocks, the continuity of basement around the eastern end of the belt, and the increase in metamorphism through the northern part of the belt into a broad area to the north. The Cape Smith volcanic rocks may have been extruded along a continental rift, parallel to a continental margin at Sugluk. Continental collison at Sugluk would have thrust the older and higher grade Sugluk rocks over the Deception gneisses, produced the broad Deception antiform, and displaced the Cape Smith rocks to the south in a series of north-dipping thrust slices.

Legacies of Slavery in North-West Uganda: The Story of the ‘one-Elevens’

Africa ◽  
2006 ◽  
Vol 76 (2) ◽  
pp. 180-199 ◽  
Author(s):  
Mark Leopold
Keyword(s):  
Northern Uganda ◽  
East African ◽  
Southern Sudan ◽  
North West ◽  
The Core ◽  
The North ◽  
Rebel Groups ◽  
The Face ◽  
History Of ◽  
The One

AbstractThis article outlines the history of a people known as ‘Nubi’ or ‘Nubians’, northern Ugandan Muslims who were closely associated with Idi Amin's rule, and a group to which he himself belonged. They were supposed to be the descendants of former slave soldiers from southern Sudan, who in the late 1880s at the time of the Mahdi's Islamic uprising came into what is now Uganda under the command of a German officer named Emin Pasha. In reality, the identity became an elective one, open to Muslim males from the northern Uganda/southern Sudan borderlands, as well as descendants of the original soldiers. These soldiers, taken on by Frederick Lugard of the Imperial British East Africa Company, formed the core of the forces used to carve out much of Britain's East African Empire. From the days of Emin Pasha to those of Idi Amin, some Nubi men were identified by a marking of three vertical lines on the face – the ‘One-Elevens’. Although since Amin's overthrow many Muslims from the north of the country prefer to identify themselves as members of local Ugandan ethnic groups rather than as ‘Nubis’, aspects of Nubi identity live on among Ugandan rebel groups, as well as in cyberspace.

scholarly journals Analisis Riwayat Waktu Gempa Sesar pada Sistem Fondasi Tiang

2021 ◽  
Vol 4 (1) ◽  
pp. 205
Author(s):  
Alfandy Firmando ◽  
Hendy Wijaya ◽  
Amelia Yuwono
Keyword(s):  
Pile Foundation ◽  
Active Faults ◽  
Time History ◽  
Earthquake Fault ◽  
The North ◽  
Lateral Forces ◽  
History Of ◽  
Internal Forces ◽  
Lower Structure ◽  
Earthquake Faults

In Indonesia, many active faults that can cause earthquakes, one of them is the Palu Koro fault which extends approximately 240 km from the north (Palu City) to the south (Malili) to the Gulf of Bone. The effect of this earthquake fault caused enormous damage to infrastructure. The lower structure, namely the foundation, is part of a structure that transmits the load received from axial and lateral forces which then continues into the ground below. This foundation plays a big role in making the structure stand firm; however, pile failures still often occur in Indonesia. Because of that in this journal will be analyzing of the time history of earthquake faults in the pile foundation system. This analysis requires the assistance of a geotechnical based program. The program can process the data provided so that it produces a result that can be analyzed. The results can be in the form of internal forces, and displacement. The result of this curve we can see the effect of the earthquake fault on the foundation. From these results, it is expected to provide data to help plan structures to be built in areas prone to earthquake faults.AbstrakWilayah Indonesia banyak terdapat sesar aktif yang dapat menimbulkan gempa salah satunya sesar aktif di Sulawesi adalah sesar Palu Koro yang memanjang kurang lebih 240 km dari utara (Kota Palu) ke selatan (Malili) hingga Teluk Bone. Pengaruh gempa sesar ini menimbulkan kerusakan yang sangat besar dalam infrastruktur. Struktur bawah yakni Fondasi ialah bagian dari suatu struktur yang meneruskan beban yang diterima dari gaya aksial dan lateral yang kemudian meneruskan ke dalam tanah di bawahnya. Fondasi inilah berperan besar membuat struktur tersebut dapat berdiri kukuh akan tetapi kegagalan tiang masih sering terjadi di Indonesia. Dengan demikian pada jurnal ini dilakukan analisis riwayat waktu gempa sesar pada sistem fondasi tiang. Analisis ini membutuhkan bantuan program berbasis geoteknik. Program dapat mengolah data-data yang diberikan sehingga menghasilkan suatu hasil yang dapat di analisis. Hasil tersebut dapat berupa kurva gaya dalam dan perpindahan. Hasil dari kurva ini kita dapat melihat pengaruh dari gempa sesar tersebut terhadap fondasi. Dari hasil tersebut diharapkan dapat memberikan data-data untuk membantu merencanakan bangunan struktur yang akan dibangun di wilayah yang rawan akan gempa sesar.

The History of Medieval Nubia

2021 ◽  
pp. 757-771
Author(s):  
Giovanni R. Ruffini
Keyword(s):  
Civil Wars ◽  
The South ◽  
The Core ◽  
The North ◽  
12Th Century ◽  
The Face ◽  
History Of ◽  
Medieval Nubia

The history of the medieval Nubian state begins as it ends, in a state of decentralization. The core of that state emerges through the unification of Nobadia in the north and Makuria in the center of the Nubian heartland, perhaps at some point in the 7th century. Makuria’s relationship with Alwa to the south is less clear, but some unification seems to have obtained there as well, in the 11th century. The Nubian state’s relationship with the wider world is variable. Nubia sometimes ignores or challenges its northern Islamic neighbors, and at other times defers to them or aggressively courts their diplomatic favor. Dotawo, the indigenous name for Nubia at least in later centuries, is still strong in the face of invasions in the 12th century, but shows signs of internal dynastic instability in later periods. Ongoing Egyptian interference in Nubian civil wars, coupled with increasing levels of Arab immigration to Nubia, destabilizes the Nubian state and returns it to its original fragmentation.

Orogen-parallel extension in the North Cascades Crystalline Core, Washington

Tectonics ◽  
1989 ◽  
Vol 8 (6) ◽  
pp. 1105-1114 ◽  
Author(s):  
E. H. Brown ◽  
J. L. Talbot
Keyword(s):  
North Cascades ◽  
The North ◽  
Crystalline Core ◽  
Parallel Extension

The Castanheira Site: New Evidence on the Antiquity and History of the Ananatuba Phase (Marajó Island, Brazil)

1969 ◽  
Vol 34 (4) ◽  
pp. 402-410 ◽  
Author(s):  
Mario F. Simões
Keyword(s):  
Geographical Distribution ◽  
Formative Period ◽  
Eastern Coast ◽  
North Coast ◽  
The North ◽  
History Of ◽  
Marajó Island ◽  
The Right ◽  
New Evidence

AbstractThe geographical distribution of the Ananatuba phase has been extended to the eastern coast of Marajó by the discovery of J-26: Castanheira on the right bank of the middle Rio Camará. Two stratigraphic cuts were excavated, and the pottery obtained was classified into the types established by Meggers and Evans (1957). The resulting seriated sequence shows trends of ceramic change parallel to theirs and a similar intrusion of Mangueiras phase sherds in the upper levels of the deposit. Interdigitation of the J-26 levels into the seriated sequence for the Ananatuba phase shows the new site to occupy a relatively late position, supporting the earlier inference of expansion from the north coast toward the southeast during the history of the phase. A charcoal sample obtained from Cut 1, Level 40-50 cm., and correlating with the appearance of Mangueiras phase sherds in the refuse, gave the date of 980 B.C. ± 200 (SI-385), which places the initial occupation of Marajó by pottery-making groups within the Formative period.

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